. A playful student throws a water balloon straight up in the air. It reaches a height of 20 meters before it comes crashing back down on the playful student.
How long was the balloon in the air? How fast was it moving when it hit the
student on the head?

What formula  this one  (x_/

It really doesn't matter for any of the questions that you've listed.

Since you have not included the experiment situation and the data, of course, i can not give you specific details about it. but i can you with this question.1) i will assume that the motion is projectile (parabolic) motion.2) yes, the horizontal distance depends on the horizontal velocity as, naming vx the horizontal velocity and t the time, it is: x = vx × t3) now, observe that the flight time depends on the vertical velocity as, naming voy the initial vertical velocity, t the time and y the vertical distance before reaching the ground: y = yo + voy×t - gt² / 2.the higher the initial vertical velocity (voy) the longer the object will be flying and so t will be higher in the equation for the horizontal distance.that explains the relationship between the horizontal distance and the horizontal velocity.